1. Field of the Invention
This invention relates generally to engraving machines, and particularly to a manually operated portable machine of superior performance, improved significantly over prior art devices by the inclusion of a unitized pneumatic motor within the body of the engraving machine.
2. Description of the Prior Art
Considerable difficulty has been encountered in the past in driving a cutter of an engraving tool at speeds sufficiently great to provide smooth chatter-free engraving within a portable machine.
Electric powered devices either direct coupled or belt driven by an electric motor, and the like, are necessarily heavy and difficult to handle from the standpoint of true portability of a manual device. Further, counter-weighted or counter-balanced mechanisms tend to encumber the operator and thereby defeat the true object of portability.
Further problems encountered in the past by conventional manually operated engraving machines involve vibration and heat. Belt driven spindles tend to vibrate when reaching speeds in excess of 20,000 rpm. Bearing friction within the spindles also tends to raise the temperature to damaging levels when rotated at speeds in excess of 20,000 rpm, thereby reducing the life expectancy of a unit to that of impracticality.
Still another and very significant problem encountered in the past with portable engravers is that of heavy, cumbersome, and tiring manipulation by even the most skilled and manually dexterous of operators due to the massiveness of the machines.
Prior patents believed to be pertinent to this invention are as follows:
2,185,011 Dec. 26, 1939 2,780,966 Feb. 12, 1957 2,884,695 May 5, 1959 3,250,008 May 10, 1966